When VTOL hover, the motor keeps breaking down

HK_Shin · November 17, 2022, 1:26am

Hi, All

A month ago, I completed the Striver mini VTOL.
HW: MFE 50A ESC x4, MFE 5008 motor x4, pixhawk4, pixhawk4 GPS(M8N), PM07, MFE carbon prop 17x5.5, CUAV C-RTK GPS,
SW: px4 v1.13.1

When flying, the aircraft looks stable, but the high-frequency noise is sometimes heard and the aircraft’s motor number 2 becomes very hot.

All wiring, ESC, and motor of the aircraft were replaced about three times, but the same symptoms occurred.
Logs: https://logs.px4.io/plot_app?log=93635fa0-8460-445e-bd20-4e67294ad775

And on the last flight, there is a log that seems to turn off the rear motor No. 2 and No. 4 when switching from FW to MC.
Logs: https://logs.px4.io/plot_app?log=a7e2f2e8-74d5-4c8b-add5-863dbe60e4b6

when aircraft hover motor output is very noisy

saengphet · November 19, 2022, 3:42am

Hi, have you tried playing around with the cutoff frequency “example: IMU_DGYRO_CUTOFF = 20, IMU_GYRO_CUTOFF = 30” or reducing the D gain of Multicopter mode or setting it to zero “MC_PITCHRATE_D, MC_ROLLRATE_D, MC_YAWRATE_D”?

I recommended you enable the flight log with a high rate (SDLOG_PROFILE) in order to plot the FFT graph, it may help you to analyze deeper.

If the problem happens only in multicopter mode, try to fly with multicopter mode only (may be easier for the analysis) in any direction and attitude to see the behavior.

HK_Shin · November 21, 2022, 1:10am

Thank you, I’ll do that

rollys · November 21, 2022, 10:37pm

Just to cover the basics, did you or have you by chance calibrated the ESCs directly from the Rx, bypassing the FC, just to make sure that the proper endpoints are configured?

Good luck.

HK_Shin · November 22, 2022, 1:14am

Hi all, We did the test last week with ESC calibration and D value down. We were able to confirm that the heat was definitely less than the original value.
I enable the flight log with a high rate
Logs: https://logs.px4.io/plot_app?log=506f811d-aaca-4b7d-b2ad-79bc2d536311
Is any problem in FFT?

saengphet · November 23, 2022, 2:07am

I think it’s good enough to test the full transition to fixed-wing again, don’t you?

HK_Shin · November 24, 2022, 1:23am

I agree. We’re going to test it soon

HK_Shin · November 24, 2022, 1:33am

This is the log data and graph of the second MFE aircraft
logs:
https://logs.px4.io/plot_app?log=54bd2bc7-a241-4e84-8786-3343f2760aa2
https://logs.px4.io/plot_app?log=e9e54d59-3357-4db4-b8c2-ce2c7574a92d
https://logs.px4.io/plot_app?log=9e54ed41-8220-4a43-adae-3ee6e64f9fa3
https://logs.px4.io/plot_app?log=5277db1e-add4-48b4-8590-5b60cc684601

The plane was more serious and the motor broke down in three minutes. I think the reason for the failure is that the PID value of the first plane was applied as it is.

The values below are the logs and graphs after adjusting the D values.
log:https://logs.px4.io/plot_app?log=3d883e6e-bb4e-4a8f-a207-d7393db01043

I’d appreciate it if anyone could advise me on the second plane

junwoo0914 · December 11, 2022, 1:03am

Oof, with the X/Y accelerometer values reaching ~5 m/s^2 magnitude, that’s a big oscillation/vibration!!

Could you please check:

What is causing this vibration (I highly suspect that the Flight Controller is mounted in an insecure way, or there’s something vibrating the whole frame heavily during flight)?